1. Field of the Invention
The present invention relates to a technology for estimating the line of sight of a person in an image.
2. Description of the Related Art
Conventionally, a technology for determining the line of sight of a person is known in which a face image including the black and the outer corner of the right and left eyes are used (for example, see Japanese Patent Application Laid-Open No. 2003-256852). However, as illustrated in FIG. 24, this conventional technology estimates only the eye direction α1 but does not consider the face direction β1. On the other hand, another technology is known in which the feature points of organs, such as the eye, are detected from the face in the image data and, using the distance between the detected feature points, the line of sight direction is estimated from both the eye direction α1 and the face direction β1 (for example, see Japanese Patent Application Laid-Open No. 2007-265367).
However, one of the problems with the conventional technology is a significant decrease in the line-of-sight detection accuracy that may be caused, for example, when the face turns sideways and one of the eyes is hidden or when the eyes are hidden by hair. Another problem is caused by the dominant eye. For example, when a person gazes in a predetermined direction, the right eye appears to look in the predetermined direction but the left eye does not appear to look in the predetermined direction.